纳米孔材料中辐射热传递的改进——扩散近似法计算

Calculation of Radiation Heat Transfer within Nanoporous Material by Modified Diffusion Approximation Method

用可燃的烧蚀材料作为主动的承热层,用不可燃的多孔材料作为被动的隔热层,是当今一次性使用航天器最普通的一种热防护形式,然而对可重复使用的航天器来说,这种防热结构显然不适用。但是如果把烧蚀层改为金属薄壁或多层金属热防护系统,在不增加很多质量的情况下,能保证航天器主结构在允许的温度范围,则可能是一种很好的设计。在此情况下,隔热层将经受更为严峻的考验。文章用改进的扩散近似法计算纳米孔材料中的辐射热,可与其他求解方法或试验结果进行比较,并为热防护设计者提供参考。

Using the flammable charring material as active acceptant layer and the inflammable porous material as passive protection layer is the common practice of thermal protection design of an expendable spacecraft, but this kind of heat protection system is obviously impractical for re- usable spacecraft. It might be appropriate if the charring layer is replaced by a metallic layer or multilayer which would keep the temperature of the main structure of the vehicle within an allow- able limit without appreciable weight increase, but that would lead the protection layer to undergo more sever heat trials. This paper uses the modified diffusion approximation to be compared cal- culate the radiative heat flow within the nanoporous protection layer, which can be used to check with the results obtained by other analytic or experimental methods to give a reference for the heat protection designers .